1. Field of the Invention
The present invention relates to an electrolytic solution including a solvent and an electrolyte salt and a battery using the electrolytic solution.
2. Description of the Related Art
In recent years, portable electronic devices such as camera-integrated VTRs (videotape recorders), cellular phones, or laptop computers are widely used, and size and weight reduction in the portable electronic devices and an increase in longevity of the portable electronic devices have been strongly demanded. Accordingly, as power sources for the portable electronic devices, the development of batteries, specifically lightweight secondary batteries capable of obtaining a high energy density have been promoted. Among them, a secondary battery (a so-called lithium-ion secondary battery) using insertion and extraction of lithium for charge-discharge reaction, a secondary battery (so-called lithium metal secondary battery) using precipitation and dissolution of lithium, or the like holds great promise, because the secondary batteries are capable of obtaining a large energy density, compared to a lead-acid battery or a nickel-cadmium battery.
As an electrolytic solution for the lithium-ion secondary battery and the lithium metal secondary battery, a combination of a carbonate-based solvent such as propylene carbonate or diethyl carbonate and an electrolyte salt such as lithium hexafluorophosphate is widely used. It is because the combination has high conductivity, and its potential is stable.
In addition, to improve various performance capabilities, some techniques relating to the composition of the electrolytic solution have already been proposed. More specifically, to improve heat stability or the like, a technique of including a sulfonyl imide compound is known (for example, refer to Japanese Unexamined Patent Application Publication No. 2002-280063). Moreover, to improve storage characteristics, a technique of including a compound having a carbon-carbon unsaturated bond and including carbon, fluorine and hydrogen is known (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-172101).
Moreover, as a peripheral technique, a technique of synthesizing various compounds using difluoroolefin as a starting material is known (for example, refer to Japanese Unexamined Patent Application Publication No. H09-067293, Angewandte Chemie International Edition, (Germany), 2004, Vol. 43, p. 5203-5206, and The Journal of Organic Chemistry, (US), 1991, Vol. 56, p. 4322-4325). According to this, a technique of synthesizing difluoroolefin is known (for example, refer to Journal of Fluorine Chemistry, (UK), 2005, Vol. 126, p. 1361-1367 and Tetrahedron Letters, (UK), 1996, Vol. 37, No. 19, p. 3223-3226).